Embodiments of the present invention relate to a method of cleaning and refurbishing process chamber components.
A substrate processing chamber is used to process a substrate in an energized process gas to manufacture electronic circuits, such as integrated circuit chips and displays. Typically, the process chamber comprises an enclosure wall that encloses a process zone into which a process gas is introduced, a gas energizer to energize the gas, and an exhaust system to exhaust and control the pressure of the gas. Components of the chamber, such as chamber walls, liners and depositions rings, are susceptible to corrosion by the energized gas used to process the substrate, especially when the process gas contains halogen species. Corrosion resistance can be improved by forming a corrosion resistant coating over the component, such as a twin-wire arc sprayed aluminum coating. The coating can also have a textured surface to which process residues adhere, thus inhibiting accumulated process residues from flaking off and contaminating the substrates being processed in the chamber.
Such coated components often require frequent cleaning and refurbishing to retain their properties. For example, when such chamber components are used in PVD processes to sputter deposit material onto a substrate from a target, the sputtered material also accumulates on the surfaces of the component. The accumulated process deposits cause thermal expansion stresses that result in delamination, cracking, and flaking-off of the coating from the underlying structure. The plasma in the chamber can penetrate through damaged areas of the coating to erode the exposed surfaces of the underlying structure, eventually leading to failure of the component. Thus, a refurbishing process is typically performed to clean and refurbish the coated component after a number of substrates have been processed. The refurbishment process may involve removing process deposits, such as sputtered material, that has accumulated on the coating surface, and re-coating the component with a corrosion resistant material. The refurbishment process reduces the incidence of spalling or peeling of the coating from the component during the processing of substrates, and thus reduces the contamination of substrates processed in the chamber.
In one conventional refurbishing process, a metal component is cleaned with an acidic and a basic cleaning solution to remove process residues accumulated on the coating as well as to dissolve and remove the metal coating from the component, as described for example in U.S. patent application Ser. No. 10/304,535, to Wang et al, filed on Nov. 25, 2002, and commonly assigned to Applied Materials, which is herein incorporated by reference in its entirety. The surface of the component is then grit blasted in a relatively harsh and aggressive bead blasting process that re-textures the surface of the component to provide a desired surface roughness, and thereby improves adhesion of a subsequently applied coating. The relatively harsh bead blasting step utilizes relatively large bead particles having a size of at least about 600 micrometers and a high bead blasting pressure of at least about 483 kPa (70 psi) to re-texture the surface and provide a surface having an average surface roughness of at least about 6.35 micrometers (250 microinches.) After bead blasting, the coating is re-applied to the component, for example in a twin wire arc spraying process.
However, a problem with the above-described process is that it typically fails to adequately remove sufficient amounts of intermetallic compounds that can develop at the interface between the metal coating and underlying metal component, and which are believed to result from thermal cycling of the parts in the process chamber. The intermetallic compounds weaken the bond between the coating and component and can cause spalling of the coating from the component, which can reduce the component part life as well as cause contamination of the substrates by the spalled coating materials. A large number of these intermetallic compounds can accumulate when process chamber temperatures above about 300° C. are used, and when processing large numbers of substrates without intervening component refurbishment steps.
Thus, it is desirable to have a process of refurbishing and cleaning a coated component to provide improved corrosion resistance of the component and a longer component chamber use life. In particular, it is desirable to have a process of refurbishing and cleaning a coated component that substantially entirely removes intermetallic compounds from the component to provide improved bonding between the coating and underlying component.